I'm pretty sure that's Wavy Gravy doing the no-nukes intro in this San Francisco acoustic set. (
http://en.wikipedia.org/wiki/Wavy_Gravy)
I like these acoustic sets. This one isn't as good as those of the fall of 1980, and the recording isn't all that great, but this was still a delight to find here. One interesting aspect is that instead of Phil on electric bass, we have John Kahn on acoustic bass.
My favs here are Deep Elem, Cassidy (always nice acoustic), a pretty To Lay Me Down, and the jamming Bird Song.
(To hear the origin of the Dead's version of On the Road Again, check out the version from 2/25/66. It features a mid-60's Beatles guitar riff with Pigpen on harmonica.
http://www.archive.org/details/gd66-02-25.sbd.unknown.1593.sbefail.shnf )